Skip to main content

Research Repository

Advanced Search

Numerical assessment of potential impacts of hydraulically fractured Bowland Shale on overlying aquifers

Cai, Zuansi; Ofterdinger, Ulrich

Authors

Ulrich Ofterdinger



Abstract

Natural gas extracted from hydraulically fractured shale formations potentially has a big impact on the global energy landscape. However, there are concerns of potential environmental impacts of hydraulic fracturing of the shale formations, particularly those related to water quality. To evaluate the potential impact of hydraulically fractured shale on overlying aquifers, we conduct realizations of numerical modeling simulations to assess fluid flow and chloride transport from a synthetic Bowland Shale over a period of 11,000 years. The synthetic fractured shale was represented by a three-dimensional discrete fracture model that was developed by using the data from a Bowland Shale gas exploration in Lancashire, UK. Chloride mass exchange between fractures and the rock matrix was fully accounted for in the model. The assessment was carried out to investigate fluid and chloride mass fluxes before, during, and after hydraulic fracturing of the Bowland Shale. Impacts of the upward fracture height and aperture, as well as hydraulic conductivity of the multilayered bedrock system, are also included this assessment. This modeling revealed that the hydraulically fractured Bowland Shale is unlikely to pose a risk to its overlying groundwater quality when the induced fracture aperture is ≤200 µm. With the fracture aperture ≥1000 µm, the upward chloride flux becomes very sensitive to the upward fracture height growth and hydraulic conductivity of the multilayered bedrock system. In the extremely unlikely event of the upward fracture growth directly connecting the shale formation to the overlying Sherwood Sandstone aquifer with the fracture aperture ≥1000 µm, the upward chloride mass flux could potentially pose risks to the overlying aquifer in 100 years. The model study also revealed that the upward mass flux is significantly intercepted by the horizontal mass flux within a high permeable layer between the Bowland Shale and its overlying aquifers, reducing further upward flux toward the overlying aquifers.

Citation

Cai, Z., & Ofterdinger, U. (2014). Numerical assessment of potential impacts of hydraulically fractured Bowland Shale on overlying aquifers. Water Resources Research, 50, 6236-6259. https://doi.org/10.1002/2013WR014943

Journal Article Type Article
Acceptance Date Jul 3, 2014
Online Publication Date Jul 9, 2014
Publication Date Jul 31, 2014
Deposit Date Apr 5, 2016
Publicly Available Date Mar 28, 2024
Journal Water Resources Research
Print ISSN 0043-1397
Electronic ISSN 1944-7973
Publisher American Geophysical Union
Peer Reviewed Peer Reviewed
Volume 50
Pages 6236-6259
DOI https://doi.org/10.1002/2013WR014943
Keywords Bowland Shale; natural gas; global energy; water quality; overlying aquifers;
Public URL http://researchrepository.napier.ac.uk/id/eprint/9788
Publisher URL http://dx.doi.org/10.1002/2013WR014943

Files

Numerical assessment of potential impacts of hydraulically fractured Bowland Shale on overlying aquifers (1.9 Mb)
PDF





You might also like



Downloadable Citations